perf: optimize _peer_to_session from std::map to std::unordered_map

[chaowyc]

Description

Replace std::map with std::unordered_map for _peer_to_session to achieve O(1) lookup performance instead of O(log n).

The peer_t type (ENetPeer*) is a pointer, which has native hash support. All operations (find, emplace, erase) are interface-compatible between std::map and std::unordered_map.

This change aligns with the code comment at line 529 which states: 'Insert this into the map for O(1) lookups in the future'

Tested:

• Interface compatibility verified with unit test
• Performance benchmark confirms expected improvements
• No API changes required (drop-in replacement)

Screenshot

N/A - This is a performance optimization with no UI changes.

Issues Fixed or Closed

N/A - This addresses a performance optimization opportunity identified through code analysis.

Roadmap Issues

N/A

Type of Change

• [ ] feat: New feature (non-breaking change which adds functionality)
• [ ] fix: Bug fix (non-breaking change which fixes an issue)
• [ ] docs: Documentation only changes
• [ ] style: Changes that do not affect the meaning of the code (white-space, formatting, missing semicolons, etc.)
• [ ] refactor: Code change that neither fixes a bug nor adds a feature
• [x] perf: Code change that improves performance
• [ ] test: Adding missing tests or correcting existing tests
• [ ] build: Changes that affect the build system or external dependencies
• [ ] ci: Changes to CI configuration files and scripts
• [ ] chore: Other changes that don't modify src or test files
• [ ] revert: Reverts a previous commit
• [ ] BREAKING CHANGE: Introduces a breaking change (can be combined with any type above)

Checklist

• [x] Code follows the style guidelines of this project
• [x] Code has been self-reviewed
• [ ] Code has been commented, particularly in hard-to-understand areas
• [ ] Code docstring/documentation-blocks for new or existing methods/components have been added or updated
• [ ] Unit tests have been added or updated for any new or modified functionality

AI Usage

• [ ] None: No AI tools were used in creating this PR
• [x] Light: AI provided minor assistance (formatting, simple suggestions)
• [ ] Moderate: AI helped with code generation or debugging specific parts
• [ ] Heavy: AI generated most or all of the code changes

[sonarqubecloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov[bot]]

Bundle Report

Bundle size has no change :white_check_mark:

[codecov[bot]]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 14.22%. Comparing base (1d6d916) to head (8934dd1). :warning: Report is 2 commits behind head on master. :white_check_mark: All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4415      +/-   ##
==========================================
- Coverage   14.94%   14.22%   -0.73%     
==========================================
  Files          63       89      +26     
  Lines       13726    18936    +5210     
  Branches     6476     8677    +2201     
==========================================
+ Hits         2052     2694     +642     
- Misses       8686    15085    +6399     
+ Partials     2988     1157    -1831     

Flag	Coverage Δ
FreeBSD-14.3-aarch64	?
FreeBSD-14.3-amd64	13.55% <ø> (+<0.01%)	:arrow_up:
Linux-AppImage	11.55% <ø> (-0.02%)	:arrow_down:
Windows-AMD64	13.34% <ø> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/stream.cpp	2.84% <ø> (ø)
src/utility.h	61.35% <ø> (+2.00%)	:arrow_up:

... and 74 files with indirect coverage changes